Metal Gated Ultra Short MOSFET Devices

ABSTRACT

MOSFET devices suitable for operation at gate lengths less than about 40 nm, and methods of their fabrication is being presented. The MOSFET devices include a ground plane formed of a monocrystalline Si based material. A Si based body layer is epitaxially disposed over the ground plane. The body layer is doped with impurities of opposite type than the ground plane. The gate has a metal with a mid-gap workfunction directly contacting a gate insulator layer. The gate is patterned to a length of less than about 40 nm, and possibly less than 20 nm. The source and the drain of the MOSFET are doped with the same type of dopant as the body layer. In CMOS embodiments of the invention the metal in the gate of the NMOS and the PMOS devices may be the same metal.

CROSS REFERENCE TO A RELATED APPLICATION

This application is a Division of application Ser. No. 11/407,473, filedApr. 20, 2006, wich is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to electronic devices. In particular itrelates to less than 40 nm gate length field effect devices and methodsof producing such structures.

BACKGROUND OF THE INVENTION

Today's integrated circuits include a vast number of devices. Smallerdevices and shrinking ground rules are the key to enhance performanceand to improve reliability. As FET (Field Effect Transistor) devices arebeing scaled down, the technology becomes more complex, and changes indevice structures and new fabrication methods are needed to maintain theexpected performance enhancement from one generation of devices to thenext. The mainstay material of microelectronics is silicon (Si), or morebroadly, Si based materials. One such Si based material of importancefor microelectronics is the silicon-germanium (SiGe) alloy.

There is great difficulty in maintaining performance improvements indevices of deeply submicron generations. Various detrimental deviceeffects become more serious with successively decreasing devicedimensions. For instance, with shortening gate lengths the so calledshort channel effects (SCEs), most notably drain-induced barrierlowering (DIBL) pose severe roadblocks to miniaturization. Also,parasitic capacitances, such as source and drain capacitance, stand inthe way of device performance. At the same time, achieving ever highergate capacitance runs into roadblocks, such as the depletion of the gatematerial, which traditionally has been poly-Si.

Traditionally, CMOS technologies advance from one generation to the nextby scaling the gate length. This is accomplished by thinning the gatedielectric, increasing the channel doping and forming shallowersource/drains. Thus far, gate dimensions have been scaled down to about40 nm by using this approach for MOSFET (Metal Oxide SemiconductorField-Effect-Transistor) devices with poly-Si gate electrodes. Manyelements needed to support the gate length scaling scheme areapproaching physical limitations. For instance, making junctions highlyconductive, and simultaneously of shallow depth, with the use of ionimplantation and annealing becomes very difficult, due to dopantactivation and diffusion effects. For standard processes, higher dopantactivation (at higher temperatures) is usually accompanied by additionaldiffusion issues and concerns. Furthermore, excessive junction leakagemay prevent channel doping from being increased beyond the concentrationneeded to control short channel effects for less than 40 nm gate lengthdevices. Thus, a new device design, architecture, and processingmethodology is needed to overcome the drawbacks associated with theprior art.

SUMMARY OF THE INVENTION

In view of the problems discussed above this invention discloses aMOSFET suitable for operation at gate lengths less than 40 nm. Such aMOSFET device includes a ground plane formed of a monocrystalline Sibased material. This ground plane has dopant impurities of aconcentration of between about 1×10¹⁸/cm³ and 1×10²⁰/cm³. A Si basedbody layer is epitaxially disposed over the ground plane with athickness of between about 2 nm and 7 nm. The body layer is doped withimpurities of opposite type than the ground plane at a concentration ofbetween about 1×10¹⁸/cm³ and 5×10¹⁹/cm³. The transition region betweenthe dopants of the ground plane and the dopants of the body layer has awidth across their interface of between about 2.5 nm and 0.5 nm. A gateinsulator layer is disposed over the body layer, and a gate is disposedover the gate insulator layer. The gate has a metal with a mid-gapworkfunction directly contacting the gate insulator layer. The gate ispatterned to a length of less than about 40 nm, and possibly less than20 nm. The source and the drain of the MOSFET are doped with the sametype of dopant as the body layer, with a concentration of between about5×10¹⁹/cm³ and 2×10²⁰/cm³. The junction depth of the source and thedrain is less than about 7 nm.

In representative embodiments of the present invention the Si basedmaterial of the device is essentially pure Si.

In CMOS embodiments of the invention the metal in the gate of the NMOSand the PMOS devices may be the same metal.

A method for fabricating a MOSFET suitable for operation at gate lengthsless than 40 nm is also disclosed. The method involves depositing byselective epitaxy a body layer of between about 2 nm and 7 nm thicknessover a ground plane, and doping the ground plane and the body layer withopposite type of doping impurities. The method further includesdisposing a mid-gap workfunction metal over the gate insulator. Themetal may be selected to be the same metal for NMOS and PMOS devices ina CMOS configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the present invention will become apparentfrom the accompanying detailed description and drawings, wherein:

FIG. 1A shows, in a schematic cross sectional view, an embodiment,including raised source/drain, of a less than 40 nm gate length MOSFET;

FIG. 1B shows, in a schematic cross sectional view, an alternateembodiment of a less than 40 nm gate length MOSFET;

FIG. 1C gives selected MOSFET device parameters as functions ofstructural parameters for selected preferred embodiments of the presentinvention;

FIG. 2 shows, in a schematic cross sectional view, a stage in theprocessing of a less than 40 nm gate length MOSFET, where a ground planehas been fabricated;

FIG. 3 shows, in a schematic cross sectional view, a stage in theprocessing of a less than 40 nm gate length MOSFET, where a counterdoped body layer has been fabricated;

FIG. 4 shows, in a schematic cross sectional view, a stage in theprocessing of a less than 40 nm gate length MOSFET, where a gateinsulator layer and a metal gate layer have been processed;

FIG. 5 shows, in a schematic cross sectional view, a stage in theprocessing of a less than 40 nm gate length MOSFET, where the gate hasbeen patterned;

FIG. 6A shows, in a schematic cross sectional view, a stage in theprocessing of a less than 40 nm gate length MOSFET, where the raisedsource/drain junctions are being formed; and

FIG. 6B shows, in a schematic cross sectional view, a stage in theprocessing of a less than 40 nm gate length MOSFET, where thesource/drain regions are hollowed for selective deposition the ofsource/drain junctions.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1A and FIG. 1B show, in a schematic cross sectional view, exemplaryembodiments of ultra short, less than about 40 nm gate length MOSFETdevices. The depicted embodiments incorporate elements that areinstrumental in achieving useful characteristics for such ultra shortgate length MOSFET devices. Embodiments of the present invention areaimed at gate lengths less than about 40 nm, with the 15 nm to 35 nmregime being preferred. It is also preferred that a mid-gap workfunctionmetal be the material which is in direct contact with the gateinsulator. The metal gate electrode is preferred due to its high carrierconcentration, which leads to low gate resistance and high gatecapacitance. The term “mid-gap” means that the workfunction of the gatematerial, in the presented embodiments the metal, has a workfunctionwhich is roughly halfway between the workfunctions of the p-type andn-type versions of the semiconductor material which forms the MOSFET.The workfunction of the gate material influences the device threshold(V_(t)). For ultra short MOSFET devices the desired threshold values areless than 0.5V, and possibly less than 0.2V. Satisfying such thresholdrequirements, coupled with fulfilling demands for high gate capacitance,and achieving acceptable short-channel effects (SCEs), such asdrain-induced barrier lowering (DIBL), necessitates the inventivecombinations of the present disclosure. These include high dopantconcentration substrate, or ground plane, a device body hosting thechannel which has the same doping type as the channel mobile carriers,and ultra shallow, sharp, junctions. The preferred doping ranges andphysical dimensions of several device components are inventive, andcontrary to the accepted teachings of the art. The sharp doping profilesneeded to realize embodiments of the present invention are made possibleby novel low temperature epitaxial techniques. In preferred embodimentsof the invention the ultra short gate MOSFET devices are combined intoCMOS configurations, in which the gates of the NMOS and PMOS devices maycomprise the same mid-gap workfunction metal.

In the art of microelectronics the material that has progressed thefarthest in miniaturization is silicon (Si). Si based materials arevarious alloys of Si in the same basic technological content as Si. Onesuch Si based material of importance for microelectronics is thesilicon-germanium (SiGe) alloy. The devices in the embodiments of thepresent invention are hosted in Si based materials, typically SiGe withan up to about 20% of Ge concentration. In exemplary embodiments of theinvention the Si based material may be essentially pure Si.

Referring to FIG. 1A and FIG. 1B, the gate 30 of the MOSFET device isdisposed over the gate insulator layer 40. The material which is indirect contact with the gate insulator layer 40 is a metal 30′ with amid-gap workfunction. Such metals are know in the art, they include W,Ta, TiN, and others. Through its workfunction value the gate metal 30′has influence over the device threshold. The indicating number 30′ showsthat the metal maybe part of a larger gate stack 30, which stack mightinclude materials such as poly-Si and poly-SiGe. In representativeembodiments the gate 30 might include only the mid-gap metal, containingno other materials. The wavy line terminating the top part of the gate30 in the figures indicates the possibility that, as known in the art,several materials, or structures may be further involved in a completedgate stack, or electrode.

The length 80 of the gate 30 may be the most important device parameterdetermining device performance. The range of gate lengths 80contemplated in representative embodiments of this invention are in therange of about 10 nm to about 40 nm, which is classified as an “ultrashort” regime in the microelectronics art. In typical embodiments of thepresented invention the gate length 80 is in the range of about 15 nm toabout 35 nm.

Further referring to FIG. 1A and FIG. 1B, the device has amonocrystalline Si based body layer 10. The body of the device hosts thechannel where the current conduction takes place along the interfacewith the gate insulator 40, on the side opposing the gate. The bodylayer 10 is epitaxially disposed over a ground plane 20. Inrepresentative embodiments the body layer 10 may be epitaxially grown onthe ground plane 20. The terms “epitaxially”, “epitaxy”, “epi”, etc.carry their customary usage: meaning the single crystal latticestructure carries across an interface. Typically in epitaxy a singlecrystal, or monocrystalline, material forms a platform onto whichanother single crystal material with matching crystallinecharacteristics is deposited by one of several techniques known in theart. Such techniques include, for instance, molecular beam epitaxy(MBE), and various types of chemical vapor depositions (CVD).

In exemplary embodiments of this invention the body layer 10 has athickness in the range of about 2 nm to about 7 nm. In typicalembodiments of the invention, the body layer 10 maybe about 5 nm thick.The body layer 10 is purposely doped with the same type of dopant as thecarriers of the device current. Accordingly, for NMOS devices the bodylayer 10 is doped with n-type impurities, such as P, As, Sb, and othersknow in the art; and for PMOS devices the body layer 10 is doped withp-type impurities, such as B, Ga, I, and others know in the art. Theconcentration of the doping impurities in the body layer 10 is selectedto be in the range of about 1×10¹⁸/cm³ to about 5×10¹⁹/cm³, withpreferred embodiments having the range of about 5×10¹⁸/cm³ to about5×10¹⁹/cm³. The selection of such dopant concentrations assures properthreshold value, good DIBL behavior, and high current carryingcapability in the devices. In this disclosure, the dopant type found inthe body layer 10, for referential purposes, is named “second type”.Where the layer underneath the gate insulator is purposefully doped tobe of the same type as the mobile channel charge, at times is referredto as “counter doped”. The general concept of counter doping, typicallyused for so called depletion type devices, was known in the art, see forinstance U.S. Pat. No. 5,780,899 to Hu. However, Hu does not teach thepresent invention.

The MOSFET device has a ground plane 20 formed of a monocrystalline Sibased material. The dopant impurities in the ground plane are of a typeopposite to the type of the mobile channel charge of the device. ForNMOS devices the ground plane is p-type, doped with impurities such asB, Ga, I, and others know in the art; while for PMOS devices the groundplane is n-type, doped with impurities such as P, As, Sb, and othersknow in the art. In this disclosure the dopant type found in the groundplane 20, for referential purposes, is named “first type”. The level ofdoping in the ground plane 20 influences important device behavioralparameters including the threshold value, and the size of DIBL. For theultra short devices of the embodiments of the present invention, theacceptable doping for the ground plane 20 may be in the range of about1×10¹⁸/cm³ to about 1×10²⁰/cm³, with the preferred doping being in therange of about 8×10¹⁸/cm³ to about 1×10¹⁹/cm³.

For the voltages encountered in the operation of ultra short devices,which are typically less than about 2V, or even less than about 1.5V,the doping concentration in the ground plane limits the depletionregions to the range of less than about 20 nm. Consequently, beyond thethickness of about 20 nm the actual thickness of the ground plane is nota critical parameter in determining device behavior, and can comfortablybe adjusted according to, for instance, ease of fabrication and design.The general concept of ground planes in MOSFET designs is known in theart, see for instance U.S. Pat. No. 6,391,752 to Colinge. However,Colinge does not teach the present invention.

Further referring to FIG. 1A and FIG. 1B, the body layer 10 and theground plane 20 have a common interface 15. Across this interface anabrupt transition between the first and the second type of dopantimpurities may be needed for the desirable operation of the MOSFETdevice. The selective epitaxial deposition of the body layer 10, and thein-situ doping of the body layer during the epitaxy may allow thedesired abrupt transition between the dopant impurities of first type inground plane 20 and the dopant impurities of the second type in bodylayer 10. In representative embodiments of the invention the region oftransition between the first type and the second type of dopantimpurities has a width across the ground plane/body layer interface 15of between about 2.5 nm and 0.5 nm. The 0.5 nm width may represent atransition over about a single monolayer of the crystal structure.

The ground plane 20 is disposed over a substrate 100. If, as preferredin the embodiments of the present invention, the ground planeelectrically isolates the device, then the nature of the substrate is ofno major importance. Typically, the substrate 100 may be a Si wafer,Si-on-insulator (SOI) structure, SiGe-on-insulator (SGOI) structure, oran insulating layer, or another support structure known in the art.

FIG. 1A shows an exemplary embodiment where the source 50 and the drain50 (both noted with the single reference numeral 50, since structurallythey are interchangeable), are of a raised type. Creating shallowsource/drain junctions by the technique of depositing material over thesource and the drain is a technique known in the art. Such a fabricationmay include a selective deposition process, an implantation, and a rapidthermal annealing, or a laser annealing. The height of the source/drainmaterial protruding over the plane of the gate insulator/body layerinterface, which interface is indicated by a dashed line in FIGS. 1A and1B, may typically be about 25 nm. Implanting into a material of suchthickness, coupled with rapid thermal annealing, or a laser annealingtechniques as known in the art, can produce the desired junctionproperties for the MOSFET devices. In exemplary embodiments of theinvention the dopant concentration in the source 50 and the drain 50 arein the range of about 5×10¹⁹/cm³ to about 2×10²⁰/cm³, with the junctiondepths 84 not exceeding about 7 nm. Junction depths are given relativeto the gate insulator/body layer interface, which interface is indicatedwith the dashed horizontal line in various figures.

In FIG. 1A the bottom of the source/drain junctions are drawn as beingslightly deeper than the plane of the interface 15 between the groundplane 20 and the body layer 10. The relative position of thesource/drain junction depth 84 compared to the body layer thicknessshould not be inferred, or limited, based on the depictions of thefigures. The junction depth 84 and the body layer thickness areindependently arrived at in various embodiments of the presentinvention, and while they both fall into roughly the same magnitude,each may be slightly larger then the other, depending on the details ofa particular embodiment. The situation when the source/drain junctiondepth 84 and the body layer thickness approximately coincide is amongstthe exemplary embodiments of the present invention.

FIG. 1B shows, in a schematic cross sectional view, an alternateembodiment where the source 50 and the drain 50 are not raised, butleveled as their top is approximately in the gate insulator/body layerinterface plane. In embodiments of the present invention these leveledjunctions have essentially the same dopant concentration and junctiondepth as junctions of the raised embodiments, namely a dopantconcentration in the range of about 5×10¹⁹/cm³ to about 2×10²⁰/cm³, andsource/drain junction depths 84 of less than about 7 nm. These type ofjunctions in typical embodiments may be fabricated by selectivedeposition of the junction material and in-situ doping.

The gate insulator 40 of the device may be similar to ones know in theart. It may contain silicon dioxide, silicon oxynitride, as well as, socalled high-k materials. The gate insulator may contain a crystallineportion, as well, as being epitaxially grown over the body layer 10.Although the gate insulator 40 may have many variation in its details,it is preferable for it to have an equivalent oxide thickness (EOT) ofless than about 1 nm. The EOT, a concept known in the art, refers to thethickness of such an SiO₂ layer which has the same capacitance per unitarea as the insulator layer in question.

FIG. 1A also depicts sidewall spacers 70 on the sides of the gateelectrode. Such structures, and their fabrication, are know in the art,and they are depicted in some of the figures, as they may, or may not,be present in various embodiments of the invention.

Further referring to FIG. 1A and FIG. 1B, the lateral extension of thedepicted MOSFET device is not shown, as indicated with the wavy lines.Any isolation technique used in the art in the fabrication of smalldevices, such as for instance, shallow trench isolation (STI), issuitable for the purposes of the embodiments of the present invention.

FIG. 1C gives selected MOSFET device parameters as the function ofstructural parameters for preferred embodiments of the presentinvention. The selected parameters of interest are the MOSFET devicethreshold at saturation V_(t)(sat), (given in units of Volts), which isthe threshold value when the drain is biased high; and the drain-inducedbarrier lowering, DIBL (given in units of milliVolts/Volts). TheV_(t)(sat) and DIBL values show that preferred embodiments of thepresent invention result in useful devices at such an ultra short gatelength as 20 nm, or at even shorter gate lengths.

FIG. 2 through FIG. 6 schematically show the fabrication steps involvedin the MOSFET devices and CMOS circuits of the embodiments of thepresent invention.

FIG. 2 shows, in a schematic cross sectional view, a stage in theprocessing of a 40 nm gate length MOSFET where a ground plane 20 hasbeen fabricated. The ground plane 20 is disposed over a substrate 100.Typically, the substrate 100 may be a Si wafer, SOI structure, SGOIstructure, or an insulating layer, or an other support structure knownin the art. Providing such a suitable substrate 100 may be the initialstage in the fabrication of the MOSFET device. The ground plane 20 maybe created by implanting suitable dopant impurities into the substrate,followed by annealing, possibly by rapid thermal means, or by lasermeans.

In alternate embodiments the ground plane 20 may be epitaxiallydeposited over the monocrystalline substrate surface. During suchdeposition the ground plane may be in-situ doped. The meaning in the artof “in-situ doping” is that the doping impurities are introduced duringthe growth process. Other suitable means for creating the ground plane20 are also known in the art, for instance layer transfer, and suchmeans may be used in embodiments of the present invention. The groundplane 20 material is a Si based semiconductor, such as SiGe, possiblyalloyed with further elements, such as C. In exemplary embodiments, theSi based semiconductor of the ground plane is essentially pure Si.

FIG. 3 shows, in a schematic cross sectional view, a stage in theprocessing of the MOSFET device where a counter doped body layer 10 hasbeen fabricated. In representative embodiments of the invention a lowtemperature in-situ doped selective epitaxy process is used to form thebody layer 10. The temperature range of the epitaxial process may bebetween about 500° C. and 650° C., and the doping range between about1×10¹⁸/cm³ and 5×10¹⁹/cm³. A preferred process for the epitaxialdeposition of the body layer 10 may be UHV-CVD (ultra-high-vacuumchemical-vapor-deposition). Such a deposition technique is described forinstance in U.S. Pat. No. 5,906,680 to B. S. Meyerson, which isincorporated herein by reference. The low temperature of the epitaxialdeposition may assure that the impurities in the ground plane 20 andthose in the body layer 10 do not inter-diffuse. For this reason, thetransition width across the ground plane/body layer interface 15 betweenthe first type and the second type of dopant impurities can be kept inthe range of about 2.5 nm to about 0.5 nm.

FIG. 4 shows, in a schematic cross sectional view, a stage in theprocessing of the MOSFET device when a gate insulator 40 has beendisposed over the body layer 10, and the gate 30 has been disposed overthe gate insulator 40. The gate insulator 40 in exemplary embodiments ofthe invention is fabricated by methods known in the art. The gateinsulator 40 may be grown, or deposited. The gate insulator 40 maycontain silicon dioxide, silicon oxynitride, as well as, so calledhigh-k materials. The gate insulator 40 may also have a crystallineportion, as it may be epitaxially grown over the body layer 10.

The fabrication may continue with the disposing of a metal layer 30′with a mid-gap workfunction over the gate insulator 40. Such metals areknow in the art, they include W, Ta, TiN, and others. Disposed over themetal layer 30′ may be other material layers that in combination withthe metal layer 30′ together form the gate stack, or gate electrode 30.

It is understood that apart from the discussed fabrication processes, alarge number of additional steps may have to be performed during thefabrication of the MOSFET devices. Such may include, for instance,cleaning, etching, patterning, and other steps, as it is known in theart. It is also understood that in the case of fabricating CMOS circuitsmost of the processes outlined here have to be done separately for boththe NMOS and PMOS devices. When one of the device types is being actedupon, the other type is usually being covered by masking. However, thismay not be the case for disposing the mid-gap workfunction metal layer30′. In preferred CMOS circuit embodiments of the invention the NMOS andPMOS devices may have an identical metal of mid-gap workfunctiondisposed over their respective gate dielectrics, and possibly, but notnecessarily, during the same processing step.

FIG. 5 shows, in a schematic cross sectional view, a stage in theprocessing of the MOSFET device where the gate has been patterned. Suchpatterning may follow lithography techniques know in the art. Typically,such a lithographic process defines the final, less than 40 nm, gatelength 80.

FIG. 6A and FIG. 6B show in a schematic cross sectional view, stages ofdiffering embodiments of the source/drain 50 processing.

Referring to FIG. 6A, the device after the gate patterning may undergosteps known in the art, such as the sidewall spacer 70 formation on thesides of the gate electrode. In representative embodiments of thepresent invention the source/drain formation involves selective materialdeposition, thereby raising the source/drain 50. The height of thesource/drain protrusion may be of about 25 nm. The raised source/drainthen will be implanted 110 with the proper dopant impurity type, usingan implant energy and dose in such a manner that after an annealingprocedure, which may be a rapid thermal annealing, or a laser annealingprocess, the source and drain junctions end up with a depth 84 which isless than about 7 nm.

Referring to FIG. 6B, in alternate embodiments of the invention adifferent approach may be employed to achieve shallow, highly dopedjunctions. In this case, material is hollowed out in the locations ofthe source/drain 50′, and a selective deposition is used to grow backthe source/drain, resulting in the completion of the embodiment as it isshown in FIG. 1B. During the growth process the desired doping level isin-situ provided. The final shallow, less than about 7 nm, junctiondepth may be reached by the proper combination of the depth of thehollowing of the source/drain regions 50′, and the deposition processparameters.

In preferred embodiments of the present invention the processes offorming of the ground plane, depositing of the body layer, forming ofthe gate insulator layer, forming of the gate, may all be carried out ina UHV-CVD system, without the breaking of the vacuum. A system capablefor such a degree of integration has been disclosed in U.S. Pat. No.6,013,134 to J. Chu et al, which is incorporated herein by reference.The integration of the fabrication process, including maintaining vacuumin the deposition system even between successive steps, may allow forthe abrupt interfaces and transitions practiced in embodiments of thepresent invention. Such an abrupt transition is, for instance, thedopant impurity type change across the ground plane/body layer interface15, which transition is of between about 2.5 nm and 0.5 nm. The 0.5 nmwidth may represent a transition over about a single monolayer of thecrystal structure.

Many modifications and variations of the present invention are possiblein light of the above teachings, and could be apparent for those skilledin the art. The scope of the invention is defined by the appendedclaims.

1. A method for manufacturing a MOSFET device, comprising: forming aground plane of a monocrystalline Si based material, and selectingdopant impurities in said ground plane to be of a first type with aconcentration of between about 1×10¹⁸/cm³ and 1×10²⁰/cm³; depositing byselective epitaxy a body layer of between about 2 nm and 7 nm thicknessover said ground plane, whereby creating an interface between saidground plane and said body layer, in-situ doping said body layer withimpurities of a second type to a concentration of between about5×10¹⁸/cm³ and 5×10¹⁹/cm³, and keeping a region of transition betweensaid first type and said second type of dopant impurities to a widthacross said interface of between about 2.5 nm and 0.5 nm; disposing agate insulator layer over said body layer; disposing a gate over saidgate insulator layer, wherein said gate comprises a mid-gap workfunctionmetal which is in direct contact with said gate insulator layer, andpatterning said gate to a length of less than about 40 nm; and forming asource and a drain, selecting dopant impurities in said source and saiddrain to be of said second type with a concentration of between about5×10¹⁹/cm³ and 2×10²⁰/cm³, and keeping the junction depths of saidsource and said drain to less than about 7 nm.
 2. The method of claim 1,further comprising the selection of said dopant impurities of said firsttype to be n-type, and said dopant impurities of said second type to bep-type.
 3. The method of claim 1, further comprising the selection ofsaid dopant impurities of said first type to be p-type, and said dopantimpurities of said second type to be n-type.
 4. The method of claim 1,further comprising the selection of said monocrystalline Si basedmaterial and said Si based body layer to be essentially of pure Si. 5.The method of claim 1, wherein said forming of said ground planecomprises epitaxial deposition and in-situ doping of saidmonocrystalline Si based material.
 6. The method of claim 1, whereinsaid forming of said ground plane comprises ion implantation andannealing of said first type of dopant impurities in saidmonocrystalline Si based material.
 7. The method of claim 1, whereinsaid depositing of said body layer is carried out by a process ofultra-high-vacuum-chemical-vapor-deposition (UHV-CVD), in a temperaturerange of between about 500° C. and 650° C.
 8. The method of claim 1,wherein said forming of said source and said drain include a selectivedeposition for raising said source and said drain, followed by ionimplanting and annealing said second type of dopant impurities.
 9. Themethod of claim 1, wherein said forming of said source and said draininclude selectively depositing a Si based material into hollowed regionsof said source and said drain, and in-situ introducing said second typeof dopant impurities into said source and said drain.
 10. The method ofclaim 1, wherein the processes of forming of said ground plane,depositing of said body layer, disposing of said gate insulator layer,disposing of said gate, are all carried out in a single vacuum system,without breaking vacuum inbetween carrying out said processes.
 11. Amethod for manufacturing a CMOS circuit, comprising: processing at leastone NMOS device comprising of: forming a ground plane of amonocrystalline Si based material, and selecting p-type impurities insaid ground plane to be of a concentration of between about 1×10¹⁸/cm³and 1×10²⁰/cm³; depositing by selective epitaxy a body layer of betweenabout 2 nm and 7 nm thickness over said ground plane, whereby creatingan interface between said ground plane and said body layer, in-situdoping said body layer with n-type impurities to a concentration ofbetween about 5×10¹⁸/cm³ and 5×10¹⁹/cm³, and keeping a region oftransition between said p-type and said n-type impurities to a widthacross said interface of between about 2.5 nm and 0.5 nm; forming asource and a drain, selecting dopant impurities in said source and saiddrain to be of n-type with a concentration of between about 5×10¹⁹/cm³and 2×10²⁰/cm³, and keeping the junction depths of said source and saiddrain to less than about 7 nm; and, processing at least one PMOS devicecomprising of: forming a ground plane of a monocrystalline Si basedmaterial, and selecting n-type impurities in said ground plane to be ofa concentration of between about 1×10¹⁸/cm³ and 1×10²⁰/cm³; depositingby selective epitaxy a body layer of between about 2 nm and 7 nmthickness over said ground plane, whereby creating an interface betweensaid ground plane and said body layer, in-situ doping said body layerwith p-type impurities to a concentration of between about 5×10¹⁸/cm³and 5×10¹⁹/cm³, and keeping a region of transition between said n-typeand said p-type impurities to a width across said interface of betweenabout 2.5 nm and 0.5 nm; forming a source and a drain, selecting dopantimpurities in said source and said drain to be of p-type with aconcentration of between about 5×10¹⁹/cm³ and 2×10²⁰/cm³, and keepingthe junction depths of said source and said drain to less than about 7nm; and, processing each of said at least one NMOS device and said atleast one PMOS device, comprising of: disposing a gate insulator layerover said body layer; disposing a gate over said gate insulator layer,wherein said gate comprises a mid-gap workfunction metal which is indirect contact with said gate insulator layer, and selecting said metalof said NMOS gate and said metal of said PMOS gate to be identicalmetals.